Call me "brother-in-law" if the name is that hard to remember.

Keiichi and Battler don't know each other well enough yet, unfortunately. However Keiichi honestly likes the other guy and cares for him, not just because he's Ange's brother but because he's a friend. Sure, they aren't close friends or good friends, but Keiichi still thinks they are friends and that they can get along very well sister issues aside.

Also he likes that Battler is rather easy to troll, it feels nice to not be the one grabbing the short end of the stick for once. He can't wait until he manages to get Battler to play another game of Old Maid and have him walk around the village dressed as a French Maid again. Because that memory is one worth of redoing. :D